import turtle
t = turtle.Pen()
my_colors = ("red","green","yellow","black")
t.width(4)
t.speed(1)
for i in range(10): #0 1 2 3 4
    t.penup()
    t.goto(0,-i*10) #0, -100,-200,-300,-400
    t.pendown()
    t.color(my_colors[i%len(my_colors)])
    t.circle(15+i*10) #100,200,300, 400,, 500
turtle.done() #程序执行完，窗口仍然在